Apparatus for producing carbon black



May 23, 1967 LYNN APPARATUS FOR PRODUCING CARBON BLACK Filed Feb. 15. 1966 FIG. 3

- RICE F. LYNN W Li ATTORNEYS FIG.

United States Patent 3 321,281 APPARATUS FOR PRUDUCING CARBQN BLACK Rice P. Lynn, R0. Box 2, San Angelo, Tex. 76901 Filed Feb. 15, 1966, Ser. No. 527,614 7 Claims. (Cl. 233-2595) This application is a continuation-in-part of my copending application, Serial No. 314,695, filed October 8, 1963, now US. Patent Number 3,254,961 issued June 7, 1966.

This invention relates to new and useful improvements in apparatus and methods for producing carbon black.

One object of the invention is to provide a new and improved apparatus and method for producing carbon black by incomplete combustion of gaseous hydrocarbons, such as natural gas.

Another object of the invention is to provide an apparatus for producing carbon black having a burner in which gases are subjected to partial combustion or thermal decomposition and wherein the gases are preheated prior to their exposure to a combustion supporting gas.

An important object of this invention is to provide, in an apparatus and method of the character set forth, means for controlling the flow of air through the apparatus and through the combustion area, and for controlling the temperature of the gases in the combustion area.

A further object of the invention is to provide an apparatus for producing carban block having a burner vessel in which the gases subjected to partial combustion or thermal decomposition are directed into a confined area through a plurality of spaced outlet nozzles disposed on the domed top of the burner and separated from the remainder of the apparatus by a substantially semi-spherical hood disposed in spaced relationship over the upper domed portion of the burner vessel to provide a semi-spherical or arcuate passage through which oxygen bearing gases are directed into a mixture with the hydrocarbon gases discharged through the outlet nozzles of the burner vessel, and wherein the area of partial combustion or thermal decomposition is cooled by air drawn into the apparatus and passing between the hood and the walls of the furnace for cooling the hood and the discharge duct or flue from the partial combustion area.

Still a further object of the invention is to provide in an apparatus of the character described wherein the hood enclosing the partial combustion area is provided with a duct or flue which communicates with the discharge outlet or flue from the furnace to suitable carbon black separating, precipitating and storage facilities.

A particular object of the invention is to provide an apparatus and a method for producing carbon black wherein oxygen bearing gases are directed between a burner and a hood for effecting partial combustion of hydrocarbon gases to produce carbon black, and wherein additional oxygen bearing gases are directed to the exterior of the hood and around the discharge duct or flue to cool the hood and flue to maintain the temperature within the semi-spherical passage or arcuate passage between the hood and burner vessel and within the flue below a predetermined value.

A further object of the invention is to provide in an apparatus of the character described means for directing the cooling air drawn into the burner against the outside of the hood covering the burner and against the outside of the stack to the flue to maintain the temperature of the 3,321,281 Patented May 23, 1967 ice gases within the hood and the stack and below a predetermined temperature.

Still another object of the invention is to provide in an apparatus and method of the character described means for drawing oxygen bearing gases into the furnace for use in effecting partial combustion or decomposition of hydrocarbon gases, for cooling the hood of the burner or furnace and the discharge stack therefrom to prevent generation of excessive heat within the semi-spherical or arcuate passage between the hood and the burner and within the stack, and wherein the means for drawing the oxygen bearing gases into the furnace also exhausts the oxygen bearing gases which have been heated by contact with the exterior of the hood and the stack from the furnace while drawing in additional oxygen bearing gas to maintain the temperature at or below a predetermined desired maximum.

Yet another object is to provide an apparatus and method of the character described wherein the flow control for introduction and exhausting of oxygen bearing gases from the exterior of the furnace through the furnace is 'adjustably controllable.

Additional objects and advantages of the invention will be readily apparent from the reading of the following description of a device constructed in accordance with the invention, and reference to the accompanying drawings thereof, wherein:

FIGURE 1 is a vertical partly sectional view of an apparatus for manufacturing carbon black embodying the invention;

FIGURE 2 is a horizontal cross-sectional view taken on line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary view partly in elevation and partly in section of the burner vessel and the hood;

FIGURE 4 is a fragmentary sectional view showing a means for adjusting the position of the hood on the burner; and

FIGURE 5 is a vertical sectional view taken on line 55 of FIGURE 2.

In the drawings, the apparatus 10 for producing carbon black embodying the invention includes a furnace 11 having a discharge conduit or flue 12 which may be connected to suitable fans or suction blowers, not shown, for removing gases and carbon black suspended or flowing in such gases from the interior of the furnace. The furnace may be provided with a suitable access door 13, whereby the housing of the furnace may be entered for service or maintenance.

The furnace has a substantially cylindrical wall portion 14 and an upwardly and inwardly sloping or frustoconical top portion 15, to whose upper end the flue or discharge conduit 12 is connected. Air inlet ducts 17 and 18, provided with suitable flow regulator valves 17a and 130, respectively, extend into the furnace in its lower end portion to provide means by which gases bearing oxygen may be introduced into the furnace. A gas duct 20 also extends into the lower portion of the furnace to supply gaseous hydrocarbons to the burner 22 disposed substantially centrally in the furnace, and a suitable regulator valve 23 is connected in the gas duct 20 to regulate the flow of the gaseous hydrocarbons into the burner.

The burner 22 includes a spherical vessel 25 mounted on four legs 26 which extend angularly outwardly from the bottom portion of the vessel. The gas duct 20 is connected to the burner at its central bottom portion as by a fitting 27 so that the gas must flow upwardly through the burner. The top or domed portion of the burner is provided with a plurality of outlet tips or nozzles whose lower reduced portions 28 extend into suitable apertures or bores 29 of the vessel and are secured to the vessel in any suitable manner, as by welding. The nozzles have outlet passages 31 which flare upwardly and outwardly so that the uppermost discharge portions of the passages are of greater diameter than the lowermost portions thereof. As a result, the gas movin upwardly through the passage 31 from the interior of the burner vessel 25 loses velocity as it moves therethrough, and has a very low exit velocity. The nozzles are all of such configurations that the passages 31 thereof all open upwardly. The nozzles are disposed in substantially uniform spaced relationship about the upper domed surface of the burner vessel. The uppermost annular row 26a of the nozzles is arranged in a circle on the vessel outwardly of the lower end of the outlet stack 35 i of a substantially semi-spherical hood 36 disposed in spaced relationship about the domed top portion of the vessel. The lowermost row or circle 2612 of nozzles is disposed above the bottom annular end of the hood 36. The hood is supported on and in spaced relation to the domed top portion of the vessel 25, to form an arcuate annular substantially semi-spherical passage 38 therebetween, by a plurality of threaded studs 40 rigidly secured to the burner vessel and which are threaded into spacer sleeves 41 on the dome. It will be apparent that when the spacer sleeves 41 are rotated in one direction they are telescoped further inwardly on the studs 40. Thus the position of the hood and the effective width or orifice of the arcuate annular passage 38 may be adjusted by adjusting the position of the hood on the vessel. The sleeves may be secured in any adjusted position on the studs by any suitable means such as set screws 42.

The outlet stack or duct 25 from the hood extends upwardly into flow communication with the discharge conduit or flue 12 from the furnace, so that all gases and other material passing upwardly through the space between the hood and the burner and upwardly through the stack 35 will pass outwardly through the exhaust 12 without communicating with the furnace exteriorly of the hood or the outlet stack. Obviously, the outlet stack 35 may have a slip joint 35a formed therein between the hood and the flue 12 to permit adjustment of the hood with respect to the burner, if desired.

The annular arcuate hood is provided wit-h a damper or flow control means for varying the ratio of flow of the air through the annular passage 38 and through the annular passage 51 between the hood and the furnace wall. The flow control means may include a plurality of arcuate segments or plates 54 whose adjacent ends overlap and which'are adjustably supported by means of bolts 55 which extend through suitable elongate aligned apertures or slots 57 in the segments 54 and in the horizontal flanges 60 of the brackets 61 rigidly secured to the hood, as by welding. The bolts are, of course, provided with nuts 63 and washers 64 which span the openings of the slots.

It will be apparent that, when the segments 54 are moved outwardly, the effective orifice of the annular flow passage 51 is decreased while the opening to the passage 38, whose lower end is defined by the outer surface of the burner vessel and the inner edges of the segments, is increased. Conversely, when the segments are moved inwardly, the flow passage 51 is increased and, if the segments 54 are moved to such positions so that they extend past the lower edge of the hood toward the outer surface of the burner surface, the effective inlet orifice of the annular passage 38 is decreased.

An exhaust conduit or vent 65 is formed in the upper inclined portion of the upper frusto-conical end wall 15 of the furnace at a point laterally spaced from the stack 35 and flue 12, and is connected to an exhaust blower or fan 70, which is driven by an electric motor or other power unit 71 supported on a mount 72, to draw air or other oxygen bearing gases through the furnace exteriorly of the burner and the hood and exteriorly of the stack 35, and thence outwardly through the exhaust conduit 65 through the fan and outwardly through an exhaust conductor or pipe 73. It will thus be seen that air or oxygen bearing gas drawn inwardly through the inlets 17 and 18 will be drawn in part upwardly through the furnace housing to the exhaust conduit 65 and be directed outwardly through the fan 70 and exhaust conductor or pipe 73.

A plurality of inwardly and upwardly inclined baflles 75 are secured to the inner wall 14 of the furnace at a position spaced above the center of the burner vessel 25, and may be a plurality of separate inwardly and upwardly inclined sections fixedly welded to the wall of the furnace, or may constitute a substantially frusto-conical section which may be suspended vertically adjusted by means of adjusting bolts secured at their lower ends to the baflles by threaded sleeves 81 and extending through the top wall 15 of the furnace and adjustable supporting sleeves or bushings 85 suitably secured to the top wall of the furnace, whereby the position of the baffle within the furnace with respect to the burner and the hood may be adjusted. Also, if desired, more than one row of such baffles may be provided, the upper positioned above and inwardly of the lower.

The oxygen as a constituent of the air is introduced into the furnace 11 through the air inlet ducts or pipes 17 and 18 at a rate controlled by the draft created by the exhaust fan '70 acting through the exhaust conduit 65 and by the exhaust through the flue 12, and may be further controlled by the valves 17a and 18a. Simultaneously, gaseous hydrocarbons, such as natural gas, are caused to flow at a rate controlled by the regulator valve 23 into the lower end of the burner vessel 25 and thence outwardly and upwardly through the passages 31 of the nozzles into the arcuate semi-spherical passage 38 between the dome of the burner vessel and the hood 36. As the oxygen bearing air flows into the furnace below the burner vessel, a portion of the oxygen is directed upwardly into the lower end of the annular passage 38 between the hood and the furnace, while a major portion of the air is drawn upwardly between the hood and the cylindrical wall 14 of the furnace and upwardly exteriorly of the hood 36 and the stack 35 to the exhaust conduit or vent 65, from which it is drawn out of the furnace and exhausted to the exterior thereof through the fan 70 and the exhaust pipe 73.

The ratio of the rates of flow of gas into the com bustion chamber or passage 38 and to the annular passage 51 exteriorly of the hood are, of course, controlled by the flow control means 50, which is adjustable in the manner previously described. If desired, also, the bolts 50 may be laterally adjusted by means of adjusting screws 90, which extend through the wall 14 of the furnace and through suitable threaded bushings 91 therein, having their inner ends engaged in threaded nuts or bushings 92 secured to the control means 50.

The oxygen bearing gases flowing into the combustion chamber flow not only outwardly and over the outer outlet nozzles 30 in the chamber 38, but also flow upwardly and between the domed outer surface of the burner vessel and the underside of the hood, and the nozzles introducing the hydrocarbon gas into the semi-spherical flow passage or combustion passage provide for a thorough mixing of air with the gaseous hydrocarbons flowing outwardly of the passageways 31 of each of the outlet nozzles and also provide for mixture of the oxygen bearing gas with the gaseous hydrocarbon flowing from each of the outlet nozzles in a desired amount to cause the incomplete combustion as hereinafter more fully explained. The oxygen bearing gas thus introduced and mixed with the gaseous hydrocarbons flowing at low velocity from the outlet nozzles 30 causes partial combustion with the gaseous hydrocarbons and raises the temperature of the gases in the combustion chamber. The oxygen bearing gas or air flows upwardly through the semi-spherical annular passage 38, where swirling or spiral movement is induced in the gases flowing therethrough as they move to the lower end of the outlet stack 35 at the upper end of the hood. This spiral movement of the hot gases and products of the partial combustion of the gaseous hydrocarbons causes them to contact the inner surfaces of the hood 36 and of the outlet or discharge stack 35, which act as a contact catalyst to cause the products of the partial combustion of the hydrocarbons to crack and form carbon black.

The rise in the temperature in the combustion chamber caused by this partial combustion of gases, of course, causes an acceleration of the velocity of the flow of gases through the discharge stack and outwardly through the exhaust flue 12. However, because of the flow of cool air introduced into the furnace by the suction or draft of the exhaust fan through the exhaust vent 65, which air flows upwardly along the exterior or outer surface of the hood 36 and along the exterior of the exhaust stack 35, control over the temperature of the gases flowing through the combustion chamber 38 and the stack 35 is possible. The air drawn in through the inlets 17 and 1S and passing upwardly along the exterior of the hood and the exterior of the exhaust stack to the exhaust vent 65 will, therefore, maintain the temperature within the combustion chamber hood and the stack at a desired maximum temperature, so that the heat or the temperature within the combustion chamber and the stack 35 from the hood is prevented from rising to excessive or undesired temperatures by the cooling etfect of the air or oxygen bearing gases flowing upwardly in the furnace exteriorly of the hood and the stack.

The inwardly inclined baffles 75 also direct the cooling air drawn inwardly through the inlets and passing along the exterior of the hood and exhaust stack against the hood and the exhaust stack to increase the heat exchange taking place between those elements and the oxygen bearing gases or air passing through the furnace exteriorly of the hood and the stack. The furnace wall and top are not insulated, so that they conduct heat from the interior of the furnace through the Wall 14 and a top 15 thereof and help to cool the gases in the furnace.

The amount and type of carbon produced by the apparatus may be varied not only by varying the rate of introduction of the gaseous hydrocarbons into the vessel, andof the oxygen bearing gases into the furnace, but also by varying or adjusting the ratio of rates of flow of the oxygen bearing gas in the annular passage or combustion chamber 38 and the cooling gases flowing along the exterior of the hood 36 and the exhaust stack 35 through the passage 51 to the exhaust duct 65.

It will, of course, be apparent that the gaseous hydrocarbons, prior to their being discharged through the passages 31 of the burner vessel, are preheated in the burner vessel 25, since they remain an appreciable length of time in the vessel due to the relative large capacity of the vessel, and since the temperature within the burner vessel is elevated due to the release of heat from the partial combustion of the gaseous hydrocarbons in the annular burner passage 38. The hydrocarbons flowing into the combustion chamber are initially ignited in any suitable manner, as by a flame introduced into the combustion chamber, access to the burner for this purpose being had through the access door 13.

It will be seen that the apparatus for producing carbon black includes a furnace 11 having a discharge duct 12 at its upper end through which the products of the partial combustion of hydrocarbon and oxygen are removed from the furnace, a burner 22 disposed in the'lower portion of the furnace and provided with gaseous hydrocarbons by means of an inlet pipe or duct 26 which extends into the 6 furnace, and the oxygen bearing gas or air inlet pipes or ducts 17 and 18 which introduce oxygen bearing gas into the furnace at controlled rates to provide for only partial combustion of the gaseous hydrocarbons.

It will also be seen that the burner vessel 25 acts as a preheater into which the hydrocarbons are admitted for preheating, that the vessel is substantially spherical and that its domed top portion has outlet nozzles which extend outwardly from the top portion and are pro vided with discharge or outlet passages 31 Whose diameter is flared and increases outwardly to the outer end of the nozzles to lower the velocity of the hydrocarbons escaping through the passages.

It will further be seen that the outer ends of the nozzles are spaced from the top portion or dome of the vessel to permit the oxygen bearing gases, such as air, to circulate between and below the upper ends of the nozzle so that the stream of gaseous hydrocarbons flowing from each nozzle is supplied with oxygen at a rate which provides for the substantially uniform partial combustion of the hydrocarbons flowing from all of the nozzles.

It will further be seen that the burner is provided with a substantially semi-spherical hood 36 which telescopes over the upper dome portion of the burner vessel to provide, with the vessel, an annular arcuate or semi spherical inwardly and upwardly arcuate combustion passage 38 through which air may flow upwardly to the nozzles and then through the annular passage to the discharge duct or stack of the hood disposed above the central top portion of the burner vessel from which the combusted gases and carbon black are conducted through the vent 12 for further treatment and storage.

It will also be seen that the volume of the annular passage 38 may be adjusted by varying the position of the hood with respect to the burner vessel top or dome, it being apparent that the volume is increased if the spacer sleeves 41 are rotated to move them outwardly on the studs 40. Likewise, it will be particularly noted that means is provided for drawing a volume of air inwardly through the inlets and upwardly through the furnace to the exhaust conduit 65, whereby the air traveling through the furnace may be controlled at the air inlets by the valves or dampers 17a and 18a, or by varying the speed of rotation of the exhaust fan, so that the cooling effect of the air passing through the furnace exteriorly of the hood 36 and the exhaust stack may be controlled to control the temperature of the partially combusted gases within the hood and exhaust stack.

Also, it will further be seen that prior to the movement of the hot gases and the carbon suspended therein from the discharge stack of the hood to the exhaust flue 12 of the furnace, they are cooled by the contact of the air passing along the exterior of the exhaust stack, and that an accurate control is provided over the oxygen bearing gas passing through the furnace through the annular combustion passage 38 and through the cooling passage 51 by control of the speed or volume of flow of air induced by the exhaust fan 73, and by control of the air introduced through the inlets 17 and 18 by means of the dampers 17a and 18a.

The foregoing description of the invention is explanatory only, and changes in the details of the construction illustrated may be made by those skilled in the art, within the scope of the appended claims, without departing from the spirit of the invention.

What is claimed and desired to be secured by Letters Patent is:

1. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace; means for introducing gas having hydrocarbons into the lower portion of said burner; a hood disposed above and about the upper portion of said burner and spaced therefrom to provide a passage therebetween; a stack extending from the hood to the discharge flue at the upper end portion of the furnace and providing closed communication between the underside of the hood and the discharge flue; means for introducing oxygen bearing gases into said furnace below said burner whereby a portion of said oxygen bearing gases enter the passage between the burner and the hood and the remainder of said oxygen bearing gases pass over the hood to the upper portion of the furnace; a draft vent at the upper portion of the furnace communicating with the interior of the furnace exteriorly of the hood and stack; means for drawing gases out of said furnace through said draft vent to control flow of oxygen bearing gases through the furnace.

2. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace; means for introducing gases having hydrocarbons into the lower portion of said burner; a hood disposed above and about the upper portion of said burner and spaced therefrom to provide a passage therebetween; a stack extending from the hood to the discharge flue at the upper end portion of the furnace and providing closed communication between the hood and the discharge flue; means for introducing oxygen bearing gases into said furnace below said burner whereby a portion of said oxygen bearing gases enter the passage between the burner and the hood and the remainder of said oxygen bearing gases pass over the hood to the upper portion of the furnace; a draft vent at the upper portion of the furnace communicating with the interior of the furnace exteriorly of the hood and stack; means for drawing gases out of said furnace through said draft vent to control flow of oxygen bearing gases through the furnace; and bafile means in said furnace inclined inwardly and upwardly above the hood and toward the stack for directing the oxygen bearing gases into heat exchanging contact with the exterior of the hood and the exterior of the stack for cooling the same.

3. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace; means for introducing gases having hydrocarbons into the lower portion of said burner; a hood disposed above and about the upper portion of said burner and spaced therefrom to provide a passage therebetween; a stack extending from the hood to the discharge flue at the upper end portion of the furnace and providing closed communication between the hood and the discharge flue; means for introducing gases including oxygen into said furnace below said burner whereby a portion of said gases including oxygen enter the passage between the burner and the hood and the remainder of said gases including oxygen pass over the hood to the upper portion of the furnace exteriorly of the stack; a draft vent at the upper portion of the furnace communicating with the furnace exteriorly of the hood and stack; means for drawing gases out of said furnace through said discharge draft vent to control flow of gases including oxygen through the furnace; and means adjacent the lower end of the hood for varying the opening of the passageway between the hood and burner.

4. An apparatus for producing carbon black including: .a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace; means for introducing gases having hydrocarbons into the lower portion of said burner; a hood disposed above and about the upper portion of said burner and spaced therefrom "to provide a passage the-rebetween; a stack extending from the hood to the discharge flue at the upper end portion of the furnace and providing closed communication between the hood and the discharge flue; means for introducing gases including oxygen into said furnace below said burner whereby a portion of said gases including oxygen enter the passage between the burner and the hood and the remainder of said gases including oxygen pass over the hood to the upper portion of the furnace; a draft vent at the upper portion of the furnace communicating with the furnace exteriorly of the hood and stack; means for drawing gases out of said furnace through said draft vent to control flow of gases including oxygen through the furnace; baflle means in said furnace inclined inwardly and upwardly above the hood and toward the stack for directing the gases including oxygen into heat exchanging contact with the exterior of the hood and the exterior of the stack for cooling the same; and means adjacent the lower end of the hood for varying the opening of the passageway between the hood and burner.

5. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace including a vessel having a domed top portion provided with outlet passageways; a hood dis-posed about said domed top portion and providing with said domed top portion of said vessel a substantially semi-spherical upwardly and inwardly arcuate passage therebetween, said arcuate passage opening downwa-rdly into the furnace above the lower end thereof; a stack connected to the upper end of the hood and extending upwardly therefrom to the discharge flue of the furnace and providing a closed flow passage between said hood and said discharge flue and communicating with the upper end of said arcuate passage; means for introducing gas having hydrocanbons to the lower portion of said vessel; means adjacent the lower end of the furnace for introducing oxygen bearing gases into the furnace; a draft vent at the upper end of the furnace in communication with the interior of the furnace above and exteriorly of the hood and exteriorly of the stack; and means connected with said draft vent for drawing oxygen bearing gases into the furnace and through the upper portion of the furnace exteriorly of the hood and the stack to cool said hood and stack.

6. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace including a vessel having a domed top portion provided with outlet passageways; a hood disposed about said domed top portion of said vessel and providing with said domed top portion a substantially semi-spherical upwardly and inwardly arcuate passage therebetween, said passage opening downwardly into the furnace above the lower end thereof; a stack connected to the upper end of the hood and extending upwardly therefrom to the discharge flue of the furnace and providing a closed flow passage between said hood and said discharge flue and communicating with the upper end of said arcuate passage; means for introducing gas having hydrocarbons to the lower portion of said vessel; means adjacent the lower end of the furnace for introducing oxygen bearing gases into the furnace; a draft vent at the upper end of the furnace in communication with the interior of the furnace above and exteriorly of the hood and exteriorly of the stack; and means connected with said draft vent for drawing oxygen bearing gases into the furnace and through the upper portion of the furnace exteriorly of the hood and the stack; and baflie means in the furnace disposed at an angle inclined inwardly and upwardly above the lower portion of the hood and adapted to direct oxygen bearing gases drawn through the furnace into heat exchanging relationship with the exterior of the hood and the exterior of the stack to cool the same.

7. An apparatus for producing carbon black including: a furnace; a discharge flue at the upper end portion of said furnace; a burner in said furnace including a vessel having a domed top portion provided with outlet passageways; a hood disposed about said domed top portion and providing therewith a substantially semi-spherical upwardly and inwardly arcuate passage therebetween, said arcuate passage opening downwardly into the furnace above the lower end thereof; a stack connected to the upper end of the hood and extending upwardly therefrom to the discharge flue of the furnace and providing a closed flow passage between said hood and said discharge flue and communicating with the upper end of said arcuate passage; means for introducing gas having hydrocarbons to the lower portion of said vessel of said burner; means adjacent the lower end of the furnace for introducing gases including oxygen into the furnace; a draft vent at the upper end of the furnace in communication with the interior of the furnace above and exteriorly of the hood and the stack; means connected with said draft vent for drawing gases including oxygen into the furnace and through the upper portion of the furnace exteriorly of the hood and the stack; and means for varying the orifice at the lower end of the arcuate passage between the hood and the burner dome.

References Cited by the Examiner UNITED STATES PATENTS 4/1951 Marsh et al. 158-104 7/1961 Balka et a1. 23209.6

' FOREIGN PATENTS 3/1957 Canada.

MORRIS O. WOLK, Primary Examiner. m R. SERNVIN, Assistant Examiner. 

1. AN APPARATUS FOR PRODUCING CARBON BLACK INCLUDING: A FURNCE; A DISCHARGE FLUE AT THE UPPER END PORTION OF SAID FURNACE; A BURNER IN SAID FURNACE; MEANS FOR INTRODUCING GAS HAVING HYDROCARBONS INTO THE LOWER PORTION OF SAID BURNER; A HOOD DISPOSED ABOVE AND ABOUT THE UPPER PORTION OF SAID BURNER AND SPACED THEREFROM TO PROVIDE A PASSAGE THEREBETWEEN; A STACK EXTENDING FROM THE HOOD TO THE DISCHARGE FLUE AT THE UPPER END PORTION OF THE FURNACE AND PROVIDING CLOSED COMMUNICATION BETWEEN THE UNDERSIDE OF THE HOOD AND THE DISCHARGE FLUE; MEANS FOR INTRODUCING OXYGEN BEARING GASES INTO SAID FURNACE BELOW SAID BURNER WHEREBY A PORTION OF SAID OXYGEN BEARING GASES ENTER THE PASSAGE BETWEEN THE BURNER AND THE HOOD AND THE REMAINDER OF SAID OXYGEN BEARING GASES PASS OVER THE HOOD TO THE UPPER PORTION OF THE FURNACE; A DRAFT VENT AT THE UPPER PORTION OF THE FURNACE COMMUNICATING WITH THE INTERIOR OF THE FURNACE EXTERORLY OF THE HOOD AND STACK; MEANS FOR DRAWING GASES OUT OF SAID FURNACE THROUGH SAID DRAFT VENT TO CONTROL FLOW OF OXYGEN BEARING GASES THROUGH THE FURNACE. 